[PATCH] Makefile: avoid running curl-config unnecessarily
On Sat, Apr 04, 2020 at 03:38:00PM +0200, Johannes Schindelin wrote:
Show 10 quoted lines
> > [1/2]: Makefile: avoid running curl-config multiple times
> > [2/2]: Makefile: use curl-config --cflags
>
> I _suspect_ that this is responsible for the build failure
>
> make: curl-config: Command not found
>
> at https://github.com/git/git/runs/556459415#step:4:674
>
> Do we need this to fix this?
Hmm, yeah. It's an unfortunate side effect of the ":=" assignment to stop repeatedly invoking curl-config. Now it's only invoked once, but it's _always_ once, even if we're not building anything that needs it.
I wonder if there's a way to expand a Makefile variable lazily, but only once...aha, with some help from the Internet, I came up with the patch below.
Show 12 quoted lines
> -- snip --
> diff --git a/ci/test-documentation.sh b/ci/test-documentation.sh
> index de41888430a..325b4cc6185 100755
> --- a/ci/test-documentation.sh
> +++ b/ci/test-documentation.sh
> @@ -11,6 +11,7 @@ filter_log () {
> -e '/^ \* new asciidoc flags$/d' \
> -e '/stripped namespace before processing/d' \
> -e '/Attributed.*IDs for element/d' \
> + -e '/curl-config: Command not found/d' \
> "$1"
> }Yes, this works, but it's rather unfortunate that we're invoking curl-config when it's not needed. Perhaps using NO_CURL in the documentation job would be better. But if the patch below isn't too disgusting, I think I prefer that approach (because it helps _any_ top-level make invocation that isn't actually building http binaries).
Junio, you may want to hold off on moving jk/build-with-right-curl to next until we resolve this one way or the other.
-- >8 --
Subject: [PATCH] Makefile: avoid running curl-config unnecessarily
Commit 94a88e2524 (Makefile: avoid running curl-config multiple times, 2020-03-26) put the call to $(CURL_CONFIG) into a "simple" variable which is expanded immediately, rather than expanding it each time it's needed. However, that also means that we expand it whenever the Makefile is parsed, whether we need it or not.
This is wasteful, but also breaks the ci/test-documentation.sh job, as it does not have curl at all and complains about the extra messages to stderr. An easy way to see it is just:
$ make CURL_CONFIG=does-not-work check-builtins
make: does-not-work: Command not found
make: does-not-work: Command not found
GIT_VERSION = 2.26.0.108.gb3f3f45f29
make: does-not-work: Command not found
make: does-not-work: Command not found
./check-builtins.sh
We can get the best of both worlds if we're willing to accept a little Makefile hackery. Courtesy of the article at:
http://make.mad-scientist.net/deferred-simple-variable-expansion/
this patch uses a lazily-evaluated recursive variable which replaces its contents with an immediately assigned simple one on first use.
Reported-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Jeff King <peff@peff.net>
---
This is our first use of eval in the Makefile, but that goes back to GNU
make v3.80, which is from 2002. I think that should be OK.
If this inlining is too gross, we could probably contain it in a function where callers would do something like:
$(eval lazy-shell-var, CURL_LDFLAGS, $(CURL_CONFIG) --libs)
That's better in the sense that there's less gobbledygook at each callsite, but worse in that it obscures the fact that it's a variable assignment. I'd probably consider going that direction if we started growing more use-cases than these two.
We could probably also stuff this into a sh
Makefile | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
Show changes to Makefile +2 −2
diff --git a/Makefile b/Makefile
index 5099f6a8f8..97dbdcd201 100644
--- a/Makefile
+++ b/Makefile
@@ -1366,12 +1366,12 @@ else
endif
ifndef CURL_LDFLAGS
- CURL_LDFLAGS := $(shell $(CURL_CONFIG) --libs)
+ CURL_LDFLAGS = $(eval CURL_LDFLAGS := $$(shell $$(CURL_CONFIG) --libs))$(CURL_LDFLAGS)
endif
CURL_LIBCURL += $(CURL_LDFLAGS)
ifndef CURL_CFLAGS
- CURL_CFLAGS := $(shell $(CURL_CONFIG) --cflags)
+ CURL_CFLAGS = $(eval CURL_CFLAGS := $$(shell $$(CURL_CONFIG) --cflags))$(CURL_CFLAGS)
endif
BASIC_CFLAGS += $(CURL_CFLAGS)
--
2.26.0.410.gc279fb3cbd
Jeff King
